1. Confirm it's actually a rental, not a purchase or a lease-to-own. The test is ownership: if you're handing the equipment back when the job or the rental period ends, it's a rental. If you're building equity toward owning it, or it's yours outright at the end of a contract, that's a different transaction entirely, a Fixed Asset or a financed purchase, not a plain expense.
2. Set up an Equipment Rental expense account if you don't have one. Chart of Accounts, New, Expenses as the account type. Some businesses lump this into a general Rent Expense account instead; either works, as long as you're consistent, so your reports mean the same thing month over month.
3. Enter the rental bill or expense. Use Bill if you're paying later, Expense if it already cleared, categorize it to the Equipment Rental account, and assign it to the job or project if you're tracking profitability (Plus and Advanced support that natively).
4. Tag it to the right job if more than one project used the equipment. Equipment rented for a specific job should get tagged to that job's cost, not sit in a general bucket, especially if the rental cost needs to roll into what you bill the client.
5. Save and let it hit the P&L in the period you rented it. Unlike a fixed asset, a rental expense doesn't get depreciated or carried on the balance sheet. It's recognized fully in the period it's incurred, same as any other operating cost.